Up to this time, Timolol maleate and Isopropyl unoprostone are known as example of compounds that have been used as agents for lowering intraocular pressure.
Recently, Bunazosin hydrochloride, which has .alpha..sub.1 -adrenoceptor blocking effect a mechanism (hereinafter referred to as .alpha..sub.1 -blocking effect) quite different from the actions of Timolol maleate and Isopropyl Unoprostone, has been developed as an agent for the treatment of glaucoma and is attracting public attention. However, Bunazosin hydrochloride was primarily developed as an agent for the treatment of hypertension. Therefore, Bunazosin hydrochloride has potent action on the blood pressure and it is wondered that it might induce side effects such as hypotension and orthostatic hypotension.
Generally, most agents for lowering intraocular pressure are topically applied as eyedrops. Even in this case an active component distributes to all over the body via the blood flow and it is expected that it shows systemic action. Therefore, it is desired that expected systemic side effects are minimized even in topical administration.
Compounds which are absorbed into eyes immediately after the application and act for a long period are most preferable so as to act topically as much as possible.
Consequently, compounds which have potent reducing effect on intraocular pressure with less incidence of side effects such as hypotension and orthostatic hypotension, are rapidly absorbed into eyes after the installation and act for a long period are mostly recommended as agents for lowering intraocular pressure.